Disease caused by Mycobacterium intracellulare is difficult to be treated with the available drugs since the organism is resistant to all of them. There is an urgent need for uncovering new drugs which are active against this disease. Studies planned in this application aim at understanding the pathogenesis of this disease. Basic drug-parasite-host interactions using macrophages, HeLa cell models and direct drug uptake studies will also be done. Detailed studies on the chemotherapeutic activity of Clofazimine and Q-3 (an analogue of Ubiquinone) are included, including a pilot clinical trial on Clofazimine. Further screening of potential new compounds in the Ubiquinone analogue series are also included.